Retrieval devices are often used to remove organic material (e.g., blood clots, tissue, and biological concretions such as urinary, biliary, and pancreatic stones) and inorganic material (e.g., components of a medical device or other foreign matter), which may obstruct or otherwise be present within a patient's body cavities or passages. For example, concretions can develop in certain parts of the body, such as in the kidneys, pancreas, ureter, and gallbladder. Minimally invasive medical procedures are used to remove these concretions through natural orifices, or through an incision, such as during a percutaneous nephrolithotomy (PNCL) procedure. Further, lithotripsy and ureteroscopy, for example, are used to treat urinary calculi (e.g., kidney stones) in the ureter of a patient.
Retrieval devices may include end effectors for grasping and manipulating objects. An exemplary end effector may have a plurality of arms that expand and contract to grasp objects within a patient.